<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>回文数</title>
</head>

<body>
  <script>
    var Pa = function (x) {
      if (x < 0) return false
      let str = '' + x
      return Array.from(str).reverse().join('') === str
    };
    console.log(Pa(121));
  </script>
</body>

</html>